Officers were called to the area of Chertsey Road in Whitton at 10.48pm on Tuesday, August 1 to reports of gunshots heard.
A spokesman for Metropolitan Police said: "Officers, including specialist firearms officers, attended but no victims or suspects were located.
"A 30-year-old man self-presented at a west London hospital with gunshot injuries.
"He has since been discharged."
Detectives from the Met Police Trident and Area Crime Command are investigating the incident.
Two males, aged 16 and 27, were arrested in connection with the investigation and have been released under investigation.
Police say enquiries into the incident continue.
Anyone with information should call police on 101 or Tweet @MetCC.
Those wishing to pass on information anonymously can do so by contacting Crimestoppers on 0800 555 111 or online .
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